JP2019135778A - Organic EL display device - Google Patents

Abstract

To provide an organic EL display device achieving a reduced resistance in a contact region of a TFT substrate and also enhancing moisture barrier properties furthermore.SOLUTION: An organic EL display device includes an organic EL display layer which is formed above a TFT substrate 1 that is obtained by forming a TFT on a substrate 2. In the TFT substrate 1, a first moisture barrier layer 6 is formed so as to cover: a gate insulating layer 4 and a gate electrode 5; a contact region of an oxide semiconductor layer 3 other than a connecting portion of the contact region connected to a source electrode 8 and a connecting portion of the contact region connected to a drain electrode 9; and a region on the substrate 2 where the oxide semiconductor layer 3 is not disposed. In the substrate 2, a second moisture barrier layer 22 is formed above a resin substrate 21, the second moisture barrier layer 22 being in contact with the oxide semiconductor layer 3 and the first moisture barrier layer 6. A cathode of the organic EL display layer is located on the inner side than the outer periphery of a region where the first moisture barrier layer 6 and the second moisture barrier layer 22 are in contact with each other.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an organic EL display device using a thin film transistor element substrate.

  In recent years, research and development of thin film transistor element substrates using an oxide semiconductor typified by In-Ga-Zn-O for a channel layer have been actively conducted. Hereinafter, the thin film transistor element substrate may be referred to as a TFT substrate. The structure of a TFT substrate using an oxide semiconductor is generally the same bottom gate structure as that of a conventional TFT substrate using amorphous silicon. However, research and development of a TFT substrate having a higher performance top gate structure that reduces the parasitic capacitance between the gate electrode, the source electrode, and the drain electrode has been actively performed (Patent Documents 1 and 2).

The TFT substrate described in Patent Document 2 will be described with reference to FIG. A TFT substrate 901 described in Patent Document 2 is a top gate TFT substrate. The TFT substrate 901 includes an oxide semiconductor layer 903 formed over a glass substrate 902, a gate insulating layer 904 and a gate electrode 905 formed over a channel region 903b in the center of the oxide semiconductor layer 903. The TFT substrate 901 further includes an aluminum oxide layer 906, an interlayer insulating layer 907, a source electrode 908, and a drain electrode 909. The source electrode 908 is joined to the contact region 903 _a1 of the oxide semiconductor layer 903 through the contact hole CH1. The drain electrode 909 is joined to the contact region 903 _a2 of the oxide semiconductor layer 903 through the contact hole CH2.

The contact regions 903 _a1 and 903 _a2 sandwiching the central channel region 903 b of the oxide semiconductor layer 903 need to have lower resistance than the channel region 903 b. Therefore, first, an aluminum layer is formed over the oxide semiconductor layer 903, the gate insulating layer 904, and the gate electrode 905 by a sputtering method. Then, the aluminum layer is subjected to heat treatment, and the aluminum layer is transformed into the aluminum oxide layer 906. At this time, the contact regions 903 _a1 and 903 _a2 are doped with aluminum, and the contact regions 903 _a1 and 903 _a2 have a lower resistance than the channel region 903 b. Thus, the TFT substrate 901 has a contact region with a relatively simple configuration and a low resistance. The aluminum oxide layer 906 also has a moisture barrier property.

JP 2009-278115 A JP 2011-228622 A

  However, the TFT substrate 901 described in Patent Document 2 has insufficient moisture barrier properties, and further improvements in moisture barrier properties are desired.

  In view of this, the present disclosure provides an organic EL display device having a TFT substrate in which the resistance of the contact region is reduced and the moisture barrier property is further improved in a top gate TFT substrate using an oxide semiconductor. .

  An organic EL display device according to one embodiment of the present disclosure includes a substrate and an oxide provided on a part of the substrate and having a channel region and a pair of contact regions sandwiching the channel region along the substrate surface A semiconductor layer; a gate electrode provided in the channel region via a gate insulating layer; a source electrode joined to one of the pair of contact regions; and a drain electrode joined to the other of the pair of contact regions; The gate insulating layer and the gate electrode are provided so as to cover the pair of contact regions of the oxide semiconductor layer, a junction between the contact region and the source electrode, and the contact region and the drain. Provided to cover the region excluding the junction with the electrode and the region on the substrate where the oxide semiconductor layer is not provided And an organic EL display layer formed on the substrate and having at least an anode, a light emitting layer, and a cathode, wherein the first moisture barrier layer comprises a metal oxide. And the first moisture barrier layer formed by the atomic layer deposition method is in contact with the pair of contact regions, and the substrate includes a resin substrate mainly composed of a resin material; A second moisture barrier layer formed on the resin substrate, wherein the second moisture barrier layer is in contact with the oxide semiconductor layer and the first moisture barrier layer, and the cathode is The first moisture barrier layer and the second moisture barrier layer are located on the inner side of the outer periphery of the region.

  In the thin film transistor element substrate according to one embodiment of the present disclosure, by simply forming the first moisture barrier layer, the resistance of the contact region of the oxide semiconductor layer in contact therewith can be reduced. In addition, since the first moisture barrier layer is formed by the atomic layer deposition method, the film quality is dense and the water vapor transmission rate is lower than that of the layer formed by the sputtering method.

  Therefore, according to the thin film transistor element substrate according to one embodiment of the present disclosure, it is possible to provide an organic EL display device including a thin film transistor element substrate that realizes a reduction in resistance of the contact region and an increased moisture barrier property. .

FIG. 1 is a cross-sectional view and an enlarged view of a main part of a TFT substrate according to the first embodiment. FIG. 2 is a diagram showing the measurement results of the water vapor transmission rate of the example and the comparative example. FIG. 3 is a schematic diagram illustrating a manufacturing process of the TFT substrate 1 according to Embodiment 1, and (a) is a cross-sectional view when the resin substrate 21 is formed on the glass substrate 100. FIG. 4B is a cross-sectional view when the first moisture barrier layer 22 is formed on the resin substrate 21. FIG. 4C is a cross-sectional view when the oxide semiconductor layer 3 is formed on a part of the first moisture barrier layer 22. FIG. 4D is a cross-sectional view when the gate insulating layer 4 and the gate electrode 5 are formed on the first region R1 of the oxide semiconductor layer 3; (E) shows a region of the first moisture barrier layer 22 where the oxide semiconductor layer 3 is not formed, the second region R2 of the oxide semiconductor layer 3, the gate insulating layer 4, and the gate electrode 5. It is sectional drawing when the 2nd moisture barrier layer 6 is formed by the atomic layer deposition method so that it may touch and may cover these. (F) is a cross-sectional view of the formation of the contact holes CH1 and CH2 to a second moisture barrier layer 6 on the contact regions 3a ₁ and 3a _2. (G) shows a source electrode 8 joined to the contact region 3a ₁ through the contact hole CH1 on the second moisture barrier layer 6, and a contact region 3a ₂ through the contact hole CH2 on the second moisture barrier layer 6. It is sectional drawing when the drain electrode 9 to join is formed. (H) is a cross-sectional view when the TFT substrate 1 is peeled from the glass substrate 100. FIG. 4 is a plan view showing the organic EL display device according to the second embodiment. FIG. 5 is a cross-sectional view of the display area of the organic EL display device according to the second embodiment. FIG. 6 is a circuit configuration diagram of subpixels of the organic EL display device according to the second embodiment. FIG. 7 is a cross-sectional view of a portion from the display region to the peripheral region of the organic EL display device according to the second embodiment. FIG. 8 is a cross-sectional view of a TFT substrate according to the prior art.

<Knowledge that forms the basis of this disclosure>
First, how the present inventor came up with the invention of each aspect according to the present disclosure will be described. Since the TFT substrate 901 described in Patent Document 2 described above includes the aluminum oxide layer 906, the TFT substrate 901 has some moisture barrier property. However, the aluminum layer before the aluminum oxide layer 906 is oxidized is a layer formed by sputtering. Therefore, the aluminum oxide layer 906 is not dense and has a relatively high water vapor transmission rate. When various displays are manufactured by forming a liquid crystal display layer, an organic EL display layer, or the like on the TFT substrate 901, moisture entering from the inside or outside of the glass substrate 902 or moisture entering through the aluminum oxide layer 906 Is a problem. When the moisture that has entered as described above reaches the liquid crystal display layer, the organic EL display layer, and the like, a problem occurs. For example, the organic EL display layer includes a cathode and an electron injection layer that are deteriorated by moisture. When moisture reaches the cathode, the electron injection layer, or the like, a non-light emitting portion (dark spot) may occur in the organic EL display layer, or the luminance may be reduced. That is, the aluminum oxide layer 906 has insufficient moisture barrier properties, and further improvement in moisture barrier properties is desired. Therefore, the present inventor has come up with the invention of each aspect according to the present disclosure described below based on the above knowledge.

  A thin film transistor element substrate according to one embodiment of the present disclosure includes a substrate, and an oxide semiconductor provided on a part of the substrate and including a channel region and a pair of contact regions sandwiching the channel region along the substrate surface A gate electrode provided in the channel region via a gate insulating layer, a source electrode joined to one of the pair of contact regions, a drain electrode joined to the other of the pair of contact regions, The gate insulating layer and the gate electrode are provided so as to cover the pair of contact regions of the oxide semiconductor layer, a junction between the contact region and the source electrode, and the contact region and the drain electrode. And a region on the substrate that is not provided with the oxide semiconductor layer. A first moisture barrier layer provided on the first moisture barrier layer, wherein the first moisture barrier layer contains a metal oxide and is formed by an atomic layer deposition method, and the first moisture barrier layer is formed by the atomic layer deposition method. The barrier layer is in contact with the pair of contact regions.

  According to this aspect, the first moisture barrier layer is provided so as to cover the gate insulating layer and the gate electrode, and the oxide semiconductor layer does not exist on the pair of contact regions of the oxide semiconductor layer and on the substrate. Are provided in the area. Since the first moisture barrier layer contains a metal oxide, the resistance of the contact region in contact with the oxide semiconductor layer can be reduced. That is, the contact region of the oxide semiconductor layer in contact with the first moisture barrier layer can be reduced in resistance only by forming the first moisture barrier layer. In addition, since the first moisture barrier layer is formed by the atomic layer deposition method, the film quality is dense, and the water vapor transmission rate is lower than that when formed by the sputtering method.

  Therefore, according to the thin film transistor element substrate according to this aspect, it is possible to provide a thin film transistor element substrate in which the resistance of the contact region is reduced and the moisture barrier property is increased.

  In another aspect of the present disclosure, the first moisture barrier layer may have a layer structure at an atomic level. Thereby, the film | membrane state of a 1st moisture barrier layer becomes dense, and a moisture barrier property becomes high.

  In another aspect of the present disclosure, the pair of contact regions in contact with the first moisture barrier layer may have a lower resistance than the channel region not in contact with the first moisture barrier layer.

  In another aspect of the present disclosure, the substrate includes a resin substrate mainly composed of a resin material, and a second moisture barrier layer formed on the resin substrate, and the second moisture barrier. The layer may be in contact with the oxide semiconductor layer and the first moisture barrier layer. As described above, by providing a region where the first moisture barrier layer and the second moisture barrier layer are in direct contact with each other, the moisture barrier property can be further improved.

  In another aspect of the present disclosure, the second moisture barrier layer may be formed by a chemical vapor deposition method or an atomic layer deposition method. Thereby, compared with the case where it forms by sputtering method, the 2nd moisture barrier layer can be made into a dense film. Furthermore, a denser film can be formed by the atomic layer deposition method, and the moisture barrier property can be improved.

  In another aspect of the present disclosure, the first moisture barrier layer and the second moisture barrier layer may have different oxides. Thereby, for example, when a foreign substance is mixed between the resin substrate and the second moisture barrier layer, the first moisture barrier layer does not reflect the raised portion of the foreign substance, and the second moisture barrier layer Deposited to cancel the swell. As a result, after the first moisture barrier layer is formed, the surface is formed with a flat shape.

  In another aspect of the present disclosure, the first moisture barrier layer includes an oxide of aluminum (Al), and the second moisture barrier layer includes an oxide of zirconium (Zr). May be.

  In addition, in the method for manufacturing a thin film transistor element substrate according to one embodiment of the present disclosure, an oxide semiconductor layer is formed over a part of the substrate, and the channel region of the oxide semiconductor layer formed over the substrate is formed. A pair of a gate insulating layer, a gate electrode formed on the gate insulating layer, the surface of the substrate on which the oxide semiconductor layer is not formed, and the channel region sandwiched between the oxide semiconductor layer and the channel region A first moisture barrier layer containing a metal oxide is formed by atomic layer deposition so as to cover each of the contact region, the gate insulating layer, and the gate electrode, and A pair of contact holes penetrating to the pair of contact regions is formed in the first moisture barrier layer, and one of the pair of contact holes is formed on the first moisture barrier layer. Forming a source electrode that joins one of the pair of contact regions, and a drain electrode that joins the other of the pair of contact regions on the first moisture barrier layer through the other of the pair of contact holes The pair of contact regions in contact with the first moisture barrier layer has a lower resistance than the channel region not in contact with the first moisture barrier layer.

  According to this aspect, the region where the oxide semiconductor layer is not formed in the second moisture barrier layer, the pair of second regions sandwiching the first region of the oxide semiconductor layer, the gate insulating layer, the gate electrode, A first moisture barrier layer is formed by atomic layer deposition so as to cover each of the layers. Accordingly, in the oxide semiconductor layer, the first region becomes a channel region, and the pair of second regions becomes a pair of contact regions. The first moisture barrier layer contains a metal oxide. By forming the first moisture barrier layer by an atomic layer deposition method, a metal in the metal oxide is doped into the oxide semiconductor layer, or oxygen in the oxide semiconductor layer is in the first moisture barrier layer. As a result, the contact region can be reduced in resistance. That is, the contact region of the oxide semiconductor layer in contact with the first moisture barrier layer can be reduced in resistance only by forming the first moisture barrier layer. In addition, since the first moisture barrier layer is formed by the atomic layer deposition method, the film quality is dense, and the water vapor transmission rate is lower than that when formed by the sputtering method.

  Therefore, according to the method of manufacturing a thin film transistor element substrate according to this aspect, it is possible to provide a thin film transistor element substrate that realizes a reduction in resistance of the contact region and an increased moisture barrier property.

  In another aspect of the present disclosure, the substrate may include a resin substrate mainly composed of a resin material and a second moisture barrier layer formed on the resin substrate.

  In another aspect of the present disclosure, the second moisture barrier layer may be formed by a chemical vapor deposition method or an atomic layer deposition method. Thereby, compared with the case where it forms by sputtering method, the 2nd moisture barrier layer can be made into a dense film. Furthermore, a denser film can be formed by the atomic layer deposition method, and the moisture barrier property can be improved.

  In another aspect of the present disclosure, the first moisture barrier layer and the second moisture barrier layer may have different oxides. Thereby, for example, when a foreign substance is mixed between the resin substrate and the second moisture barrier layer, the first moisture barrier layer does not reflect the raised portion of the foreign substance, and the second moisture barrier layer Deposited to cancel the swell. As a result, after the first moisture barrier layer is formed, the surface is formed with a flat shape.

  In another aspect of the present disclosure, the first moisture barrier layer includes an oxide of aluminum (Al), and the second moisture barrier layer includes an oxide of zirconium (Zr). May be.

  In addition, an organic EL display device according to an aspect of the present disclosure includes at least a thin film transistor element substrate according to an aspect of the present disclosure described above, an anode, a light emitting layer, and a cathode formed on the thin film transistor element substrate. An organic EL display layer. Accordingly, it is possible to provide an organic EL display device including a thin film transistor element substrate that realizes a reduction in resistance of the contact region and an increased moisture barrier property.

  In another aspect of the present disclosure, in a plan view, the cathode may be located inside an outer periphery of a region where the first moisture barrier layer and the second moisture barrier layer are in contact with each other. Accordingly, the cathode that is likely to be deteriorated by moisture can be positioned inside the outer periphery of the region where the first moisture barrier layer and the second moisture barrier layer are in contact with each other. Can be increased.

  In another aspect of the present disclosure, the organic EL display layer further includes an electron injection layer, and the electron injection layer includes the first moisture barrier layer and the second moisture barrier in a plan view. You may be located inside the outer periphery of the area | region which a layer contact | connects. As a result, the electron injection layer that easily deteriorates due to moisture can be positioned inside the outer periphery of the region where the first moisture barrier layer and the second moisture barrier layer are in contact with each other. Moisture barrier properties can be increased.

Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the drawings.
<Embodiment 1>
(Configuration of TFT substrate 1)
A TFT substrate 1 according to the first embodiment will be described with reference to FIG. The TFT substrate 1 includes a substrate 2, an oxide semiconductor layer 3 provided on a part of the substrate 2, a gate insulating layer 4 provided on a channel region 3 b that is a central portion of the oxide semiconductor layer 3, and a gate. It has an electrode 5. The TFT substrate 1 further includes a region on the substrate 2 where the oxide semiconductor layer 3 is not provided, a contact region 3 _a1 on the oxide semiconductor layer 3 where the gate insulating layer 4 is not provided, and 3 a ₂ and a first moisture barrier layer 6 covering the gate insulating layer 4 and the gate electrode 5. The TFT substrate 1 further has a source electrode 8 and a drain electrode 9 on the first moisture barrier layer 6. Contact holes CH1 and CH2 pass through the first moisture barrier layer 6 so as to reach the contact regions _3a1 and _3a2 of the oxide semiconductor layer 3, respectively. In the contact hole CH1, the source electrode 8 and the contact region _3a1 are joined. In the contact hole CH2, the drain electrode 9 and the contact region _3a2 are joined. The TFT 1 is a so-called top gate type (staggered structure) TFT.

The substrate 2 includes a resin substrate 21 (hereinafter, referred to as a resin substrate 21) mainly composed of a resin, and a second moisture barrier layer 22 formed thereon. As a material of the resin substrate 21, for example, polyimide, polyamide, aramid, polyethylene, polypropylene, polyvinylene, polyvinylidene chloride, or the like can be used. In addition, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene sulfonic acid, silicone, acrylic, epoxy, phenol and the like may be used. Two or more of these materials may be mixed, and these materials may be chemically modified. One or two or more of these materials may be combined to form a resin substrate 21 having a multilayer structure. As the material of the second moisture barrier layer 22, zirconium oxide (ZrO _x ), aluminum oxide (AlO _x ), or the like can be used. The second moisture barrier layer 22 has a function of preventing penetration of moisture and the like through the resin substrate 21 and above the resin substrate 21.

  The substrate 2 has a two-layer structure including a resin substrate 21 and a second moisture barrier layer 22 formed thereon. However, it is not limited to this. The substrate 2 may have a single layer structure such as glass, synthetic quartz, or silicon with a thermal oxide film. Other multilayer structures may be used.

The oxide semiconductor layer 3 is formed on the second moisture barrier layer 22. The oxide semiconductor layer 3, a channel region 3b under the gate electrode 5 and the gate insulating layer 4, and a contact region 3 _a1 and 3 _a2 Metropolitan sandwiching the channel region 3b. Contact regions 3 _a1 and 3 _a2 have lower resistance than channel region 3 b. That is, the contact regions 3 _a1 and 3 _a2 have a higher carrier concentration than the channel region 3 b. As a material of the oxide semiconductor layer 3, In—Ga—Zn—O, In—Ti—Zn—O, Zn—O, In—Ga—O, In—Zn—O, or the like can be used. Taking the case of In—Ga—Zn—O as an example, the constituent ratio of each element is, for example, In _x Ga _y Zn _z O _{1.5x + 1.5y + z} (x, y, and z are integers). .

The gate insulating layer 4 is provided on the channel region 3 b of the oxide semiconductor layer 3. As a material of the gate insulating layer 4, SiO _x , SiO _x N _y , TaO _x or the like can be used. The gate insulating layer 4 is formed with a single layer structure or a multilayer structure using these oxide materials.

  The gate electrode 5 is provided on the gate insulating layer 4. As a material of the gate electrode 5, aluminum (Al), molybdenum (Mo), tungsten (W), MoW, copper (Cu), titanium (Ti), chromium (Cr), or the like can be used. The gate electrode 5 is formed with a single layer structure or a multilayer structure using these metal materials. The side surfaces of the gate insulating layer 4 and the gate electrode 5 are aligned, and are separated from the source electrode 8 and the drain electrode 9. Therefore, the parasitic capacitance between the gate electrode 5 and the source electrode 8 and between the gate electrode 5 and the drain electrode 9 can be reduced.

The first moisture barrier layer 6 is formed on the second moisture barrier layer 22 where the oxide semiconductor layer 3 is not formed, and contact regions 3 _a1 and 3 _{a2 of} the oxide semiconductor layer 3 and gate insulation. The layer 4 and the gate electrode 5 are covered. As a material of the first moisture barrier layer 6, a metal oxide can be used. In the first embodiment, aluminum oxide (AlO _x ) is used.

The source electrode 8 is provided on the first moisture barrier layer 6. The source electrode 8 is joined to the contact region 3 _a1 of the oxide semiconductor layer 3 through the contact hole CH1. As the material of the source electrode 8, Al, Mo, W, MoW, Cu, Ti, Cr, or the like can be used. The source electrode 8 is formed using these metal materials so as to have a single layer structure or a multilayer structure.

The drain electrode 9 is provided on the first moisture barrier layer 6. The drain electrode 9 is joined to the contact region 3 _a2 of the oxide semiconductor layer 3 through the contact hole CH2. As the material of the drain electrode 9, Al, Mo, W, MoW, Cu, Ti, Cr, or the like can be used. The drain electrode 9 is formed with a single layer structure or a multilayer structure using these materials.

The first moisture barrier layer 6, before forming the contact holes CH1 and CH2 so as to reach the oxide semiconductor layer 3, formed on the entire surface of the oxide semiconductor layer 3 of the contact regions 3 _a1 and 3 _a2 It had been. The first moisture barrier layer 6 is, for example, AlO _x . During the formation of the first moisture barrier layer 6, Al is doped from the first moisture barrier layer 6 into the contact regions 3 _a1 and 3 _a2 of the oxide semiconductor layer 3 in contact with the first moisture barrier layer 6, or It is considered that oxygen is extracted from the oxide semiconductor layer 3. The contact regions 3 _a1 and 3 _a2 doped with Al or oxygen extracted have a lower resistance than the channel region 3 b. This fact is supported by experiments. In addition, the phenomenon that metal is doped in the contact region or oxygen is extracted from the oxide semiconductor layer is considered to occur not only in AlO _x but also in other metal oxides. As a result, the contact regions 3 _a1 and 3 _a2 have a carrier concentration higher than that of the channel region 3 b, and appropriate ON / OFF characteristics of the TFT can be obtained.

The first moisture barrier layer 6 has a function of preventing moisture and the like from entering the substrate 2 through the substrate 2. AlO _x is usually formed by sputtering. AlO _x formed by this sputtering method also has a certain degree of moisture barrier property, but it cannot be said that it is practically sufficient. Therefore, AlO _x used as the first moisture barrier layer 6 is formed by an atomic layer deposition method (hereinafter referred to as an ALD method). As shown in the enlarged view of the region T surrounded by the one-dot chain line in FIG. 1, the film formed by the atomic layer deposition method has a layer structure at the atomic level. Therefore, the film state is dense and the moisture barrier property is high. Examples of metal oxides that can be formed by the ALD method include TiO _x , CaO _x , HfO _x , TaO _x , LaO _x , and YO _x in addition to AlO _x .

  FIG. 2 shows the measurement results of the water vapor transmission rate of the sample of the example in which the aluminum oxide single film was formed by the ALD method and the sample of the comparative example formed by the sputtering method. The measurement method was a commonly known Ca (calcium) test. In this Ca test, the water vapor transmission rate is calculated from the slope at which Ca becomes conductive to nonconductive due to moisture that has permeated through the membrane to be measured. As can be seen from the measurement results in FIG. 2, the sample of the example has a water vapor transmission rate that is about three orders of magnitude lower than that of the sample of the comparative example, although the film thicknesses are almost the same. For this reason, the TFT substrate 1 of Embodiment 1 has a very excellent moisture barrier property. A region where the second moisture barrier layer 22 and the first moisture barrier layer 6 are in direct contact is considered to have a higher moisture barrier property. The second moisture barrier layer 22 may be formed by a chemical vapor deposition method (Chemical Vapor Deposition method, hereinafter referred to as a CVD method), but a denser film is formed by the ALD method. It is possible to increase the moisture barrier property.

The second moisture barrier layer 22 and the first moisture barrier layer 6 may be composed of the same oxide or different oxides. For example, ZrO _x may be used as the second moisture barrier layer 22, and AlO _x may be used as the first moisture barrier layer 6. A case is assumed in which foreign matter is mixed between the resin substrate 21 of the substrate 2 and the second moisture barrier layer 22. Then, the second moisture barrier layer 22 is deposited so as to locally protrude only that portion, reflecting the foreign matter. On the second moisture barrier layer 22, the first moisture barrier layer 6 made of an oxide different from the oxide constituting the second moisture barrier layer 22 is formed. Then, the first moisture barrier layer 6 is deposited so as to cancel the rise of the second moisture barrier layer 22 without reflecting the portion raised by the foreign matter. As a result, after the formation of the first moisture barrier layer 6, the surface of the first moisture barrier layer 6 has a flat shape. This is presumably because the degree of crystal lattice growth and the lattice constant differ for different oxides.

(Manufacturing process of TFT substrate 1)
A manufacturing process of the TFT substrate 1 according to the first embodiment will be described with reference to FIGS.

First, as shown in FIG. 3A, a glass substrate 100 is prepared. The material of the glass substrate 100 is, for example, quartz glass, non-alkali glass, high heat resistant glass, or the like. It is not preferable that impurities such as sodium and phosphorus contained in the glass substrate are mixed in the second moisture barrier layer 22. Therefore, an undercoat layer made of SiN _x , SiO _y , SiO _y N _x, or the like may be formed on the outermost surface of the glass substrate 100 (the surface in contact with the second moisture barrier layer 22). The film thickness of the undercoat layer may be, for example, about 100 nm to 2000 nm. Then, polyimide was applied on the glass substrate 100 by a spin coating method. And it heated at the heating temperature of 400 degreeC for 8 hours, and obtained the resin substrate 21 with a film thickness of 18 micrometers. The film thickness of the resin substrate may be in the range of about 1 μm to 1000 μm. If it is thinner than 1 μm, mechanical strength cannot be obtained. If it is thicker than 1000 μm, it becomes difficult to bend, and a flexible substrate cannot be obtained. As a method for forming the resin substrate 21, a stock solution may be applied as in the spin coating method, or a resin substrate that already exists as a resin substrate may be pressure bonded. In the case of pressure bonding, the adhesive layer may be formed between the glass substrate 100 and the resin substrate 21 and then bonded. The adhesive layer is not particularly limited as long as a desired adhesive strength can be obtained, such as silicone or acrylic.

Next, as shown in FIG. 3B, a ZrO _x film was formed as the second moisture barrier layer 22 by the ALD method. Tetrakisethylmethylaminozirconium was used as a precursor. The film thickness of ZrO _x was set to about 60 nm.

  Next, as illustrated in FIG. 3C, In—Ga—Zn—O was formed as the oxide semiconductor layer 3 to a thickness of about 60 nm by a sputtering method. Thereafter, patterning was performed by a photolithography method. As a method for forming the oxide semiconductor layer 3, a laser ablation method or a CVD method may be used in addition to the sputtering method. The film thickness of the oxide semiconductor layer 3 may be in the range of about 10 nm to 300 nm.

Next, as illustrated in FIG. 3D, a gate insulating film was formed over the oxide semiconductor layer 3 by a CVD method. SiO _x was used as a material for the gate insulating film. For example, SiO _x can be formed by introducing silane gas (SiH ₄ ) and nitrous oxide gas (N ₂ O) at a predetermined concentration ratio. The film thickness of SiO _x was about 100 nm. As the gate insulating film, in addition to SiO _x , SiN _x , SiO _x N _y , or a layer thereof may be stacked. The thickness of the gate insulating film may be about 50 nm to 400 nm. Subsequently, a gate electrode film was formed on the gate insulating film. As the gate electrode film, 60 nm of MoW was formed. The film thickness of the gate electrode film may be about 20 nm to 100 nm. Then, the gate electrode film was patterned by photolithography. As a patterning method for the gate electrode film, a wet etching process using a phosphorous nitrate acetic acid solution or a dry etching process using a gas such as sulfur hexafluoride (SF ₆ ) or chlorine (Cl ₂ ) may be used. . For patterning the gate insulating film, for example, a dry etching process using a gas such as sulfur hexafluoride (SF ₆ ) or a wet etching process using hydrofluoric acid (HF) may be used. After the gate electrode film was patterned by a wet etching process, the gate insulating film was patterned by a dry etching process. As a result, the gate insulating layer 4 and the gate electrode 5 were formed on the first region R1 of the oxide semiconductor layer 3 as shown in FIG.

Next, as shown in FIG. 3E, an AlO _x film was formed as the first moisture barrier layer 6 by the ALD method. Trimethylaluminum was used as a precursor. The film thickness of AlO _x was about 30 nm. By forming the AlO _x film, the pair of second regions R2 that are not covered by the gate insulating layer 4 in the oxide semiconductor layer 3 are doped with Al from the AlO _x film to reduce the resistance. As a result, in the oxide semiconductor layer 3, the channel region 3b is generated in the first region R1, and the contact regions _3a1 and _3a2 are generated in the pair of second regions R2. An inorganic insulating film or an organic insulating film may be formed on the first moisture barrier layer 6. By forming these layers, the parasitic capacitance between the gate electrode 5 and the source electrode 8 and between the gate electrode 5 and the drain electrode 9 is further reduced. In addition, it is possible to prevent short-circuiting between electrodes through foreign matter. For example, on the first moisture barrier layer 6 made of AlO _x , SiO _x may be formed to about 200 nm by CVD.

Next, as shown in FIG. 3 (f), the first moisture barrier layer 6 on the contact regions 3 _a1 and 3 _a2, by photolithography, the contact hole CH1 penetrating to the contact regions 3 _a1 and 3 _a2 And CH2.

  Next, as shown in FIG. 3G, three layers of MoW, Al, and MoW were stacked to form a source electrode film and a drain electrode film. The film thickness of the source electrode film and the drain electrode film was about 500 nm. Thereafter, patterning of the source electrode 8 and the drain electrode 9 was performed by a wet etching process using a phosphorous acetate solution.

Finally, as shown in FIG. 3H, the TFT substrate 1 was peeled from the glass substrate 100 to complete the TFT substrate 1. As a peeling method, an excimer laser or a solid laser may be irradiated from the glass substrate side, or the TFT substrate 1 may be mechanically peeled from the end using a hand or a device.
<Embodiment 2>
(Configuration of the organic EL display device 101)
FIG. 4 is a plan view of an organic EL display device 101 manufactured using the TFT substrate 1 of the first embodiment. The organic EL display device 101 includes a display area in which subpixels 102 are arranged in a matrix and a peripheral area surrounding the display area. In addition, a sealing member 103 is disposed on the outer peripheral portion of the peripheral region, and plays a role of preventing entry of moisture, gas, and the like from the outside. The sealing member 103 is made of a dense resin material (for example, a silicone resin, an acrylic resin, or the like) or glass. FIG. 5 is a cross-sectional view of the cross section taken along line A1-A2 in the enlarged view S1 of one subpixel 102 as seen in the direction of the arrow. The sub-pixels 102 are partitioned by a grid-like partition wall 107. FIG. 7 shows a cross-sectional view of one subpixel 102 adjacent to the peripheral region and an enlarged view S2 of the peripheral region adjacent to the subpixel 102. FIG. 7 is a cross-sectional view of the B1-B2 cross section in the enlarged view S2 as seen in the direction of the arrow.

  As shown in FIG. 5, the organic EL display device 101 includes a TFT substrate 1, a planarization layer 104, an organic EL display layer 200, a sealing layer 113, a sealing resin 114, and a resin substrate in order from the bottom. 21. The organic EL display layer 200 includes an anode 105, a hole injection layer 106, a hole transport layer 108, a light emitting layer 109, an electron transport layer 110, an electron injection layer 111, and a cathode 112 in order from the bottom. Have. The organic EL display layer 200 further includes a partition wall 107 for partitioning each subpixel 102. The organic EL display device 101 is a top emission type. The TFT substrate 1 in FIG. 5 has at least one more TFT 2 (not shown in FIG. 5) in addition to the TFT substrate 1 described in the first embodiment. FIG. 6 shows a circuit configuration in the sub-pixel 102. The TFT 1 is a switching transistor, and the TFT 2 is a driving transistor. The TFT 1 is connected to the TFT 2 and the capacitor C, and is further connected to a source signal line SL and a gate signal line GL connected to any one of the drive circuits (not shown). The TFT 2 is connected to the capacitor C, the TFT 1, the organic EL display layer 200, and the power signal line PL that supplies a large current from the outside. The drain electrode 10 of the TFT 2 is joined to the anode 105 of the organic EL display layer 200 in the contact hole CH3 penetrating the planarization layer 104 (see FIG. 5).

  Each layer of the organic EL display device 101 will be described in detail with reference to FIG. 5 in order from the bottom. Since the TFT substrate 1 has already been described in the first embodiment, description thereof is omitted.

  The planarization layer 104 is formed to insulate the TFTs 1 and 2 and various signal lines from the anode 105 and planarize a step due to the TFTs and the like. The planarization layer 104 is made of polyimide resin, acrylic resin, or the like. The thickness of the planarizing layer 104 is about several μm.

  The anode 105 is provided on the planarization layer 104. Examples of the material of the anode 105 include metals such as Mo, Al, Au, Ag, and Cu, alloys thereof, organic conductive materials such as PEDOT-PSS, ZnO, and lead-added indium oxide. A film made of these materials is formed by a vacuum evaporation method, an electron beam evaporation method, an RF sputtering method, a printing method, or the like. The anode 105 may have light reflectivity. The anode 105 is formed in a matrix for each subpixel.

A so-called functional layer is formed on the anode 105. In the functional layer, in FIG. 5, a hole injection layer 106, a hole transport layer 108, a light emitting layer 109, an electron transport layer 110, and an electron injection layer 111 are laminated in order from the bottom. As the hole injection layer 106, for example, copper phthalocyanine can be used, and as the hole transport layer 108, for example, α-NPD (Bis [N- (1-Naphthyl) -N-Phenyl] benzidine) can be used. The light emitting layer 109 is made of an organic material. As the organic material, for example, an oxinoid compound, a perylene compound, a coumarin compound, or the like can be used. In addition, azacoumarin compounds, oxazole compounds, oxadiazole compounds, perinone compounds, pyrrolopyrrole compounds, naphthalene compounds, anthracene compounds, and the like may be used. In addition, fluorene compounds, fluoranthene compounds, tetracene compounds, pyrene compounds, coronene compounds, quinolone compounds and azaquinolone compounds, pyrazoline derivatives and pyrazolone derivatives, rhodamine compounds, and chrysene compounds may be used. In addition, a phenanthrene compound, a cyclopentadiene compound, a stilbene compound, a diphenylquinone compound, a styryl compound, a butadiene compound, a dicyanomethylenepyran compound, and a dicyanomethylenethiopyran compound may be used. In addition, a fluorescein compound, a pyrylium compound, a thiapyrylium compound, a serenapyrylium compound, a telluropyrylium compound, an aromatic ardadiene compound, an oligophenylene compound, a thioxanthene compound, and a cyanine compound may be used. In addition, a fluorescent substance such as an acridine compound, a metal complex of an 8-hydroxyquinoline compound, a metal complex of a 2-bipyridine compound, a complex of a Schiff base and a group III metal, an oxine metal complex, or a rare earth complex may be used. As the electron transport layer 110, for example, an oxazole derivative can be used. As the electron injection layer 111, for example, Alq ₃ or the like can be used. Here, the electron injection layer 111 may be doped with an alkali metal or alkaline earth metal having a low work function in order to improve the electron injection efficiency. For example, Li, Ba, Ca, Mg, etc.

  A cathode 112 is formed on the electron injection layer 111. For the cathode 112, for example, a translucent metal oxide such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide) can be used. Moreover, you may use alloys, such as Mg-Ag. Mg has a low work function and is suitable as a cathode.

A sealing layer 113 is formed on the cathode 112. The sealing layer 113 is a layer for covering and sealing the organic EL display layer 200 and preventing the organic EL display layer from being exposed to moisture, air, or the like. The material, SiN _x, made of a transparent material such as SiO _x N _y.

  The sealing resin 114 adheres the TFT substrate 1 on which the organic EL display layer 200 or the like is formed and the resin substrate 21 facing the TFT substrate 1.

  Since the resin substrate 21 has been described in the first embodiment, the description thereof is omitted.

  The partition wall 107 is made of an insulating organic material (for example, an acrylic resin, a polyimide resin, a novolac type phenol resin, or the like). Then, it is formed at a position adjacent to the region where the light emitting layer 109 is provided. The partition wall 107 according to the second embodiment is a pixel bank having a cross-beam structure, but may be a stripe-shaped line bank.

  Next, the part from the display area of the organic EL display device 101 to the peripheral area will be described with reference to FIG. The position of the arrow C is the boundary between the display area and the peripheral area. The position of the arrow D is the end of the region where the electron transport layer 110, the electron injection layer 111, and the cathode 112 are stacked. The position of the arrow B2 is the end of the region where the second moisture barrier layer 22 and the first moisture barrier layer 6 are laminated. A sealing member 103 is formed from the position of the arrow E to the position of the arrow B2.

  Here, in the organic EL display layer 200, at least one of the electron injection layer 111 and the cathode 112 is easily deteriorated by moisture. As described above, an alkali metal or an alkaline earth metal having a low work function may be used for the electron injection layer 111 and the cathode 112. These metals are active against moisture. For example, when a material containing Ba is used for the electron injection layer 111 and ITO is used for the cathode 112, the electron injection layer 111 is easily deteriorated by moisture. In the case where an organic material is used for the electron injection layer 111 and an Mg—Ag alloy is used for the cathode 112, the cathode 112 is likely to be deteriorated by moisture. Therefore, the region where the electron injection layer 111 and the cathode 112 are provided is preferably provided on a region having a high barrier property against moisture transmitted through the resin substrate 21. The region where the second moisture barrier layer 22 and the first moisture barrier layer 6 are in contact has a particularly high moisture barrier property.

  Therefore, when both the electron injection layer 111 and the cathode 112 are likely to be deteriorated with respect to moisture, the inner side of the end B2 of the region where the second moisture barrier layer 22 and the first moisture barrier layer 6 are in contact with each other. The electron injection layer 111 and the cathode 112 are preferably provided. That is, when the organic EL display device 101 is viewed in plan, the electron injection layer 111 and the cathode 112 are located on the inner side of the outer periphery B2 of the region where the second moisture barrier layer 22 and the first moisture barrier layer 6 are in contact ( It is preferably provided in a region where the first moisture barrier layer 6 and the second moisture barrier layer 22 are in contact with each other.

  When only the electron injection layer 111 is easily deteriorated with respect to moisture, when the organic EL display device 101 is viewed in plan, the electron injection layer 111 includes the second moisture barrier layer 22 and the first moisture barrier layer. 6 is preferably provided on the inner side (in the region where the first moisture barrier layer 6 and the second moisture barrier layer 22 are in contact) with respect to the outer periphery B2 of the region where the 6 is in contact.

  Further, when only the cathode 112 is easily deteriorated with respect to moisture, the second moisture barrier layer 22 and the first moisture barrier layer 6 are in contact with each other when the organic EL display device 101 is viewed in plan. It is preferable to be provided on the inner side (in the region where the first moisture barrier layer 6 and the second moisture barrier layer 22 are in contact) with respect to the outer periphery B2 of the region.

  With the above configuration, an organic EL display device having a high barrier property against moisture entering from the outside can be realized. In the second embodiment, since the resin substrate 21 is used, it is possible to realize a flexible display having features such as lightness, thinness, not cracking, and bending.

<Other matters>
(1) Although the top emission type organic EL display device has been described in the second embodiment, the present invention is not limited to this. The present invention can also be applied to a bottom emission type organic EL display device.

  (2) An example of the method of manufacturing the organic EL display device in the second embodiment is as follows. As described in the first embodiment, first, the TFT substrate 1 is formed over the glass substrate 100. Thereafter, the planarizing layer 104, the organic EL display layer 200, the sealing layer 113, and the sealing member 103 are formed on the TFT substrate 1 by a general manufacturing process without peeling the TFT substrate 1 from the glass substrate 100. . And the resin substrate 21 is affixed on the TFT substrate 1 on which the above layers and sealing members are formed via the sealing resin 114 from the side opposite to the glass substrate 100. Finally, the glass substrate 100 is peeled off to complete a flexible organic EL display device.

  (3) The thin film transistor element substrate, the manufacturing method thereof, and the organic EL display device using the thin film transistor element substrate according to the present disclosure may be configured by appropriately combining the partial configurations of the embodiments. . In addition, the materials, numerical values, and the like described in the embodiments are merely preferable examples, and are not limited thereto. Further, the configuration can be appropriately changed without departing from the scope of the technical idea of the present disclosure. The present disclosure can be widely used for all organic EL display devices including a thin film transistor element substrate.

  The organic EL display device including the thin film transistor element substrate according to the present disclosure can be widely used as a display device for a television set, a personal computer, a mobile phone, and the like.

DESCRIPTION OF _SYMBOLS 1 Thin-film transistor element (TFT) board | substrate 2 Board | substrate 21 Resin board | substrate 22 2nd moisture barrier layer 3 Oxide semiconductor layer 3 _a1 , 3 _a2 Contact region 3 _b Channel region 4 Gate insulating layer 5 Gate electrode 6 1st moisture barrier layer 8 Source electrode 9, 10 Drain electrode 101 Organic EL display device 105 Anode 109 Light emitting layer 111 Electron injection layer 112 Cathode 200 Organic EL display layer R1 First region R2 Second region CH1, CH2, CH3 Contact hole

Claims (5)

A substrate,
An oxide semiconductor layer provided in a part on the substrate and having a channel region and a pair of contact regions sandwiching the channel region along the substrate surface;
A gate electrode provided in the channel region via a gate insulating layer;
A source electrode joined to one of the pair of contact regions;
A drain electrode joined to the other of the pair of contact regions;
The gate insulating layer and the gate electrode are provided so as to cover the pair of contact regions of the oxide semiconductor layer, a junction between the contact region and the source electrode, and the contact region and the drain electrode. A first moisture barrier layer provided so as to cover a region excluding the bonding portion and a region on the substrate where the oxide semiconductor layer is not provided;
An organic EL display layer formed on the substrate and having at least an anode, a light emitting layer, and a cathode,
The first moisture barrier layer includes a metal oxide and is formed by an atomic layer deposition method, and the first moisture barrier layer formed by the atomic layer deposition method is in contact with the pair of contact regions,
The substrate has a resin substrate whose main component is a resin material, and a second moisture barrier layer formed on the resin substrate,
The second moisture barrier layer is in contact with the oxide semiconductor layer and the first moisture barrier layer,
The organic EL display device, wherein the cathode is located inside an outer periphery of a region where the first moisture barrier layer and the second moisture barrier layer are in contact with each other. The organic EL display layer further has an electron injection layer,
2. The organic EL display device according to claim 1, wherein the electron injection layer is located inside an outer periphery of a region where the first moisture barrier layer and the second moisture barrier layer are in contact with each other.   The organic EL display device according to claim 1, wherein the first moisture barrier layer and the second moisture barrier layer are composed of different oxides.   The organic EL display device according to claim 3, wherein the first moisture barrier layer includes an oxide of aluminum (Al).   The organic EL display device according to claim 4, wherein the second moisture barrier layer has an oxide of zirconium (Zr).

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